Bulging tyres

captainfirecat
captainfirecat Posts: 44
edited August 2013 in Road beginners
Hi all

So I was doing my first monthly maintenance after buying my Carrera race bike and checked the tyre pressures. The front one read 70psi, which made me pause as it was at 130psi when I bought it. Assuming it was a misread I unhooked and rehooked, still 70psi. So I inflated to 130 (the max per the tyre) and put the bike away.

20 minutes later there was a bang, my tyre had burst (so the second reading was wrong too, not sure why...). That's when the real fun began...

I put a new tube in, put the tyre back on, started to inflate. At 20 I did a check of the tyre and found a bulge at the valve, where the tyre was further away from the wheel than the rest of the tyre. So I deflated, checked the tyre, all set into the rims (the valve section was a little away, but it always seems to be when the tyre is flat). Reinflated to 20, same problem.

So tyre off, started again... Same issue. Basically the inch or two around the valve seems to inflate sideways but not up, and while the whole tyre is nicely seated at 20 psi, the bit on the valve is a good few mm away from the wheel.

What's going on? I'm using the same tubes as are in my back wheel and as I used to use on my previous Carrera.

Comments

  • imposter2.0
    imposter2.0 Posts: 12,028
    Probably sidewall damage as a result of banging them up to 130psi. Unless you weigh 20st, you probably don't need anything like that amount of pressure...
  • andy9964
    andy9964 Posts: 930
    When fitting the tyre, are you pushing the valve into the rim to allow the tyre to seat itself properly.
    If you are, it might be a problem with the beading on the tyre, or damage to the wheel rim
  • thistle_
    thistle_ Posts: 7,149
    Andy9964 wrote:
    When fitting the tyre, are you pushing the valve into the rim to allow the tyre to seat itself properly.
    +1, for tyres that haven't previously exploded though.
    Don't do the nut thing up all the way on the valve, it holds the inner tube tight against the rim and won't let it go into the main body of the tyres, and stops the tyre hooking onto the rim. Only do it up once the tyre is inflated.

    I'm surprised the tyre didn't split if exploded. If it's not the innertube preventing the tyre seating itself I'd get a new tyre, they're not that expensive.

    Dropping from 130 psi to 70 psi in a month doesn't sound like anything to be too concerned about. Road innertubes lose pressure quickly because they are small volume and high pressure so a little leak will have more of an effect than it would on an MTB innertube, or a car tyre.
  • Andy9964 wrote:
    When fitting the tyre, are you pushing the valve into the rim to allow the tyre to seat itself properly.
    +1, for tyres that haven't previously exploded though.
    Don't do the nut thing up all the way on the valve, it holds the inner tube tight against the rim and won't let it go into the main body of the tyres, and stops the tyre hooking onto the rim. Only do it up once the tyre is inflated.

    I'm surprised the tyre didn't split if exploded. If it's not the innertube preventing the tyre seating itself I'd get a new tyre, they're not that expensive.

    Dropping from 130 psi to 70 psi in a month doesn't sound like anything to be too concerned about. Road innertubes lose pressure quickly because they are small volume and high pressure so a little leak will have more of an effect than it would on an MTB innertube, or a car tyre.

    Oh, in that case maybe the reading was right. I assumed the bang was from over inflation.

    I'm taking the wheel to Halfords tomorrow and they can give an opinion. Given the bike, inner tube and tyre all came from there if something has failed I'd hope they will replace it (I'll swallow the cost of a new tube if that's all it takes, but if it's a new wheel or tyre needed... Well, we'll see!).
  • Andy9964 wrote:
    When fitting the tyre, are you pushing the valve into the rim to allow the tyre to seat itself properly.
    If you are, it might be a problem with the beading on the tyre, or damage to the wheel rim

    Btw, could you elaborate on what you mean? I put the tube round the wheel and push the valve through the hole, then I confess I think I did put the nut on... Though very loosely...

    Hmmm, before I embarrass myself with Halfords I'll have one more go in the morning before I go out. I'll take the nut off completely and give it one last inflate!

    Thanks all for your help, I'll see how tomorrow goes.
  • pnev
    pnev Posts: 236
    Is it the virtuoso with the white tyres?
  • andy9964
    andy9964 Posts: 930
    Andy9964 wrote:
    When fitting the tyre, are you pushing the valve into the rim to allow the tyre to seat itself properly.
    If you are, it might be a problem with the beading on the tyre, or damage to the wheel rim

    Btw, could you elaborate on what you mean? I put the tube round the wheel and push the valve through the hole, then I confess I think I did put the nut on... Though very loosely...

    Hmmm, before I embarrass myself with Halfords I'll have one more go in the morning before I go out. I'll take the nut off completely and give it one last inflate!

    Thanks all for your help, I'll see how tomorrow goes.
    You have the tyre fitted over the tube.
    Don't tighten the nut at all, push the valve into the rim/tyre. This will help prevent the tube getting nipped between the tyre and rim when you inflate it.
    Pump it up a little, then push it again (just to be sure) then continue to your desired pressure.
    Put the nut on when finished
  • philwint
    philwint Posts: 763
    If you will pardon my crude artistic skills, howabout a sketch to help

    152023987.KM5LA0OD.valve.jpg

    The thing is that there is a good sized lump or rubber where the valve meets the thin tube. This blob gets in the way of the tyre seating it's self. So you need to push the valve right in to get it out of the way while you sort the tyre out.

    The nut is a slightly contentious. Some will say you don't need it, other will say it stops any rattling noises. I tend not to bother with it as I can't hear any rattles, and it's one more thing to do when fixing a puncture.

    On the pressure thing - a 10-20psi drop over a week isn't unusual. I tend to quickly top-up my tyres pretty much every other ride.
  • philwint wrote:
    If you will pardon my crude artistic skills, howabout a sketch to help

    152023987.KM5LA0OD.valve.jpg

    The thing is that there is a good sized lump or rubber where the valve meets the thin tube. This blob gets in the way of the tyre seating it's self. So you need to push the valve right in to get it out of the way while you sort the tyre out.

    The nut is a slightly contentious. Some will say you don't need it, other will say it stops any rattling noises. I tend not to bother with it as I can't hear any rattles, and it's one more thing to do when fixing a puncture.

    On the pressure thing - a 10-20psi drop over a week isn't unusual. I tend to quickly top-up my tyres pretty much every other ride.

    You are and we're both spot on, even when I had taken the tyre off and on again I had still managed to have the tube tight against the wheel, so exactly as you said, it was inflating in the wheel not the tyre. Tried again this morning and it worked perfectly after I had pushed the valve almost completely into the tyre. Should I replace the tube (will I have weakened it), or will it have survived the ordeal intact (I never went above 20 PSI).

    Incidentally, I'm going to aim for 110-120 (as I used to), mainly because that last 10 psi is a nightmare to get to :). The tyre says min 100, max 140, so 120 sounds ideal!

    Thanks all for your patience!
  • andrewjoseph
    andrewjoseph Posts: 2,165
    Tyre pressure depends on tyre size, your weight and the road conditions. I have 25mm Tyres pumped to 85f /90r and I weigh 79kg. I reduce the pressure a bit for wet rides. I use similar pressures on my 35mm touring Tyres when fully loaded with an extra 12kg.

    The ideal pressure for you will cause a slight bulging of the tyre when you sit on the bike.
    --
    Burls Ti Tourer for Tarmac, Saracen aluminium full suss for trails
  • Tyre pressure depends on tyre size, your weight and the road conditions. I have 25mm Tyres pumped to 85f /90r and I weigh 79kg. I reduce the pressure a bit for wet rides. I use similar pressures on my 35mm touring Tyres when fully loaded with an extra 12kg.

    The ideal pressure for you will cause a slight bulging of the tyre when you sit on the bike.
    I'll bear that in mind, thanks!
  • Druidor
    Druidor Posts: 230
    Got mine pumped to 100psi.

    Portly character 101kg
    ---
    Sensa Trentino SL Custom 2013 - 105 Compact - Aksium Race